Image forming apparatus including fixing device having shutter and lock member for holding shutter position

Abstract

An image forming apparatus includes a fixing device, a shutter, a lock member and an attachment member. The fixing device is supported by an apparatus main body. The shutter is movable to a close position and to an open position. The lock member is movable to a holding position holding the shutter to the close position and an allowable position allowing the shutter to move from the close position to the open position. The lock member is moved to the holding position to hold the shutter to the close position in a state where the attachment member is detached from the apparatus main body. In the middle of attaching the attachment member to the apparatus main body, the attachment member moves the lock member from the holding position to the allowable position and then moves the shutter from the close position to the open position.

The invention claimed is: 
     
       1. An image forming apparatus comprising:
 a fixing device which is supported by an apparatus main body and includes a heating rotating body by which a toner image is fixed on a sheet; 
 a shutter movable to a close position covering the heating rotating body and to an open position exposing the heating rotating body; 
 a lock member movable to a holding position holding the shutter to the close position and an allowable position allowing the shutter to move from the close position to the open position; and 
 an attachment member detachably attached to the apparatus main body, wherein 
 the lock member is moved to the holding position to hold the shutter to the close position in a state where the attachment member is detached from the apparatus main body, 
 in the middle of attaching the attachment member to the apparatus main body, the attachment member moves the lock member from the holding position to the allowable position and then moves the shutter from the close position to the open position, 
 the shutter is turned around a turning shaft to the close position and the open position, 
 the lock member makes a seesaw motion around a rotating axis to the holding position and to the allowable position and is biased to make a seesaw motion from the allowable position to the holding position, 
 the attachment member has: 
 a releasing protrusion which causes the lock member to make a seesaw motion from the holding position to the allowable position against a biasing force of the biasing member; and 
 an opening/closing protrusion which turns the shutter from the close position to the open position after the lock member makes a seesaw motion to the allowable position, 
 the lock member has: 
 a lock piece restricting a turning of the shutter from the close position to the open position; and 
 an actuation piece being pushed down by the releasing protrusion, and 
 when the actuation piece is pushed down by the releasing protrusion, the lock member makes a seesaw motion around the rotating axis and the lock piece is separated from the shutter. 
 
     
     
       2. The image forming apparatus according to  claim 1 , wherein
 the shutter and the lock member are provided in the fixing device. 
 
     
     
       3. The image forming apparatus according to  claim 1 , comprising:
 a biasing member biasing the shutter to be turned to the closing position. 
 
     
     
       4. The image forming apparatus according to  claim 1 , wherein
 the shutter has a protrusion piece which turns the shutter from the close position to the open position by being pushed by the opening/closing protrusion, and 
 the protrusion piece is arranged above the turning shaft. 
 
     
     
       5. The image forming apparatus according to  claim 4 , wherein
 the protrusion piece is inclined to an upstream side in an attachment direction of the attachment member. 
 
     
     
       6. The image forming apparatus according to  claim 1 , wherein
 the attachment member is a drum unit including a photosensitive drum and a housing storing the photosensitive drum, and 
 the releasing protrusion and the opening/closing protrusion are integrally provided in the housing. 
 
     
     
       7. An image forming apparatus comprising:
 a fixing device which is supported by an apparatus main body and includes a heating rotating body by which a toner image is fixed on a sheet; 
 a shutter movable to a close position covering the heating rotating body and to an open position exposing the heating rotating body; 
 a lock member movable to a holding position holding the shutter to the close position and an allowable position allowing the shutter to move from the close position to the open position; 
 a drum unit including a photosensitive drum and a housing storing the photosensitive drum; and 
 a frame provided between the drum unit and the fixing device, wherein 
 the lock member is moved to the holding position to hold the shutter to the close position in a state where the drum unit is detached from the apparatus main body, 
 in the middle of attaching the drum unit to the apparatus main body, the drum unit moves the lock member from the holding position to the allowable position and then moves the shutter from the close position to the open position, and 
 when the drum unit is attached to the apparatus main body, a duct between the shutter, the drum unit and the frame is formed, through which cooling air is passed. 
 
     
     
       8. The image forming apparatus according to  claim 7 , wherein
 the shutter is turned around a turning shaft to the close position and the open position, 
 the lock member makes a seesaw motion around a rotating axis to the holding position and to the allowable position and is biased to make a seesaw motion from the allowable position to the holding position, and 
 the drum unit has: 
 a releasing protrusion which causes the lock member to make a seesaw motion from the holding position to the allowable position against a biasing force of the biasing member; and 
 an opening/closing protrusion which turns the shutter from the close position to the open position after the lock member makes a seesaw motion to the allowable position. 
 
     
     
       9. An image forming apparatus according to  claim 8 , wherein
 the releasing protrusion and the opening/closing protrusion are integrally provided in the housing.